BANGOR, Maine —The newest FDA-approved treatment for opiate addiction — a once-a-month shot that blocks opioid receptors in the brain — has been on the market for more than two years but is seeing little use in Maine, where drug addiction is on the rise.

“Vivitrol is nothing new. It’s just a chemical in a delivery form that is new,” Dr. Joseph Py, corporate medical director for Discovery House, which has clinics in Bangor, South Portland, Calais and Waterville, said recently.

The Food and Drug Administration in October 2010 approved Vivitrol as a monthly shot treatment for those addicted to prescription painkillers, such as Oxycontin and oxycodone, as well as heroin, morphine and other drugs.

It also has been used since 2006 to treat alcohol dependence.

Vivitrol is different from methadone, a narcotic that has been used for three decades as a maintenance tool that helps with cravings and withdrawals, and suboxone, a combination narcotic and opiate blocker that satisfies the body’s craving for opiates without delivering a euphoric high for those who are addicted.

Both methadone and suboxone have success rates in treating opioid addiction, but they are also diverted to the streets, drug enforcement officials have said.

Vivitrol is not a replacement narcotic, and it’s not addictive. An individual cannot get high while on Vivitrol even if he or she takes drugs, and a person for whom it has been prescribed must not have taken a drug for at least a week before starting the medication.

It is to be used to “prevent relapse of opioid dependency, after opioid detoxification,” the Vivitrol website states.

The problem is that “most people who come to us are in the throes of [withdrawal],” said Dr. Vijay Amarendran, a psychiatrist at The Acadia Hospital in Bangor, which operates one of the state’s nine methadone clinics.

The opioid addiction treatment has no potential for abuse and sale on the street, because it’s not a narcotic. It can be prescribed by any doctor, unlike methadone, which is administered through clinics, or suboxone, which requires a doctor to have special certification.

A big hurdle for Vivitrol is its price.

“It’s $1,500 a treatment,” Amarendran said.

“It’s very expensive,” Py said. “It’s anywhere from $900 to $1,500. I don’t see how that can be justified. Methadone is much cheaper.”

Methadone has a weekly cost of around $115 per patient, or $460 a month, but that amount does not take into consideration transportation costs to get to and from a clinic on a daily basis or the time used.

There is also an insurance requirement that other treatments be tried first, according to Kelly Kenney, director of outpatient services at The Acadia Hospital.

“They want to make sure you’ve done your due diligence beforehand,” she said.

Because the opioid addiction treatment is relatively new, Py said Discovery House operators are being cautious.

“The more something has fanfare, the longer I wait to see how it does,” he said. “I like to wait a year. One of our clinics [outside of Maine] would like to start it within a year, a pilot, then we’ll see if it has a utility at our other clinics.

“It appears it will have utility,” he said. “I think it will have a utility in a majority of people who are opiate-free.”